In earlier sample tests, the amounts of reagents required in chemical analysis, formulation of reagent, chemical synthesis, detection of reaction, and so forth are in milliliter to microliter order. In such test-tube-scale tests, microscopic reaction sites are formed by application of technologies such as a lithographic process and a thick-film process. Thus, nanoliter-order tests have recently become practicable. A technology called micro total analysis system (μ-TAS) in which such microscopic reaction sites are utilized is applied to the fields of, for example, medical tests and diagnosis including genetic tests, chromosome tests, and cell tests, and biotechnologies including tests for very small amounts of substances contained in the environment, investigations of environments in which crops and the like are grown, and genetic tests for crops. In earlier test technologies, reagents are handled basically relying on the skill of testing technicians. The procedure of such a test, however, is complicated, and expertise in the operation of testing instruments is necessary. In contrast, μ-TAS is attracting attention as a technology that produces great advantages in terms of automation, high speed, high accuracy, low costs, quickness, reduced impact on the environment, and so forth.
To conduct a test with a flow path device employing the μ-TAS technology while utilizing the fluorescence intensity, noise fluorescence emitted from any matter other than the sample liquid needs to be suppressed because the intensity of fluorescence from a nanoliter-order sample is weak. To suppress noise fluorescence, PTL 1 discloses a flow path device 110 (see FIGS. 7 and 8) in which light-shielding portions 116 are provided on a substrate 111 having a flow path 113 in such manner as to extend along the flow path. Thus, fluorescence emitted from the substrate 111 is blocked with the light-shielding portions 116.
FIGS. 7 and 8 illustrate the flow path device 110 disclosed by PTL 1. In PTL 1, a joining method in which no adhesive is used, such as hot pressing, is employed. In such a joining method, joining surfaces 111a of the substrates 111 and 112 to be joined to each other need to be completely flat, as illustrated in sectional view in FIG. 8, or the substrates 111 and 112 need to be sufficiently deformable in response to an external action performed when the substrates 111 and 112 are joined (for example, the substrates 111 and 112 need to be made of resin). That is, if the substrates 111 and 112 are made of a brittle material such as quartz, a step of flattening the joining surfaces 111a of the substrates 111 and 112 is necessary after the light-shielding portions 116 are formed. For example, after the light-shielding portions 116 are formed on the substrate 111, another material may be provided thereover with a larger thickness than the light-shielding portions 116 and the surface of the material may be ground. For another example, portions of the substrate 111 may be removed in advance to a depth corresponding to the thickness of the light-shielding portions 116, and, after the light-shielding portions 116 are formed, the resulting body may be ground so as to remove unnecessary part and flatten the surface. In either way, a flattening step is necessary. Such a method is disadvantageously troublesome and costly.
Meanwhile, PTL 2 discloses a flow path device that is manufactured using adhesive and includes a light-shielding layer. In PTL 2, no specific method of manufacturing the flow path device is disclosed, and whether or not any wiring patterns and so forth are included in the device is unknown.